Slide rule



Feb. 13, 1940. c. P. BERG SLIDE 'RULE Filed Aug. 8, 1935 s sheets-sheet 1 Feb. 13, 1940. c. P. BERG 2,190,281

1 SLIDE RULE Filed Aug. 8, 1935 5 Sheets-Sheet 2 Feb. 13, 1940. |p BERG SLIDE RULE Filed Aug. e, 1935 s 'sheets-Shen s PatentedFeb. 13, 1940 l UNITED STAT-Es amaai suns nous omi-um am. chiosco, IIL

Application August 8,

3Ciaims.

s My invention relates to an improvement in slide rules and has for one purpose the provision of a slide rule, or its equivalent, marked or calibrated to permit the determination of a wide 5 variety of classes of information, on the basis o! past experience. My invention may be applied, for example, to' obtaining an average of past costs, to assist in bidding on furture work, as in engineering, erecting, or the like. Another purpose or application of my invention is to ascertain the time necessary for particular operations in connection with manufacturing, engineering 0r the like. As will later appear, my invention may be applied to the determination of a wide variety of facts, Where material is available for building up a scale or calibration which willexpress past performance or past experience or past averages. This material, whether it relates to the weight or value or.cost per pound, expressed in dollars, or to any other oi' a wide variety of 'types of information, where it represents the average o! past performance, may be expressed, for-example, in logarithmic scales, and I have found it practical to construct a slide rule wherein such scales may be employed in order to determine from past experience the approxi-- mate cost oi a given job, or the approximate l time which will go into a given job or opera-y tion or sequence of operations.

As will later appear, my invention may be applied to the determination of almost any variety of facts, where material is available for'building up a 'graph or a curve or a scale or an average which will express past perfomance or past experience. In considering one particular application of my invention, namely to erection engineering, for example the manufacture and erection o suchinstallations as conveyors, coal preparation plants, elevators, traveling bridges and the like, a particular firm may have cost records and time records running back for decades. Where such material is now available, however, l it may be necessary for anyone who wishes to use ity to fumble through thousands of cards and records in order to build up the necessary averages. It is impossible to do this accurately in a v short time, and there is an overwhelming tend ency, even in important and well run organiza 1935, Serial No. 35,277 (CL 235-84) very large contract, or a series of contracts, at a price which will not produce a prout'.

In the present description of my invention I describe it as applied to the determination of the. direct labor price or` cost, per pound, of a pre- 5 determined product. In other words, more broadly stated, I determine the price `or cost per unit of weight stated in a unit of currency. AI also apply my invention to the determination of the total hours for a given job or operation or sel0 quence o! operations. This is of assistance not merely in bidding, but in scheduling work. It will be realized, however, that such applications of my invention are primarily illustrative, and that my invention may be applied readily to a wide Il variety of performance, industrial, commercial or scientific. l

In taking together and analyzing the data of a particular plant, in relation to labor costs and time, I developed an equation which substan- 90 tially satisfied all the curves or graphs that I plotted to express the past averages. This equation which I employ is as follows: j

In this equation P, for example, may equal u the price or cost per pound stated in dollars. M is a constant for a class or group. W may be employed to express the weight, size, volume or number of units oi' a given job or lot of work.

In applying .this equation to my slide rule I have employed two variants oi' it as follows:

In these equations P equals price, for example, 35 price per pound in dollars, or price per unit. M

is a constant or avclass or group, and W is the weight, size, volume or number of units in alot or body of work.

I found itpractical to construct a slide rule o whereon the solution o! both equations can be directly read. I will not in the present description go into the details of the construction of logarithmic scales, as Athe construction oi such scales is not per se part of the' present invention. 4,5 But'the logarithmic scales applied to the herein illustrated slide rule may be consideredk to represent the average of pastA performance, in the matter of costs, and in the matter of time taken for certain operations, over a period of years.

I illustrate my invention more or less diagrammaticallyin the accompanying drawings, wherein- Figure 1 is a view of one disc or slide rule member, the bottom in the series later shown;

Figure 4 is a view of the complete slide rule; Figure' is a vertical axial section illustrating the assembly of the discs; and

Figure 6 is a detail of the pointer.

l Like parts are indicated by like 'symbols throughout the specification and drawings.

In considering the detailed use of the particular slide rule shown in the present drawings and described herein, it will be understood that it is adapted to perform two quite dierent operations. The rst, which involves only the bottom disc A and the intermediate disc B is the deter.

mination of the price or labor cost per pound,l

expressed in dollars, of a particular job. The scale or calibration upon which the nal result for its operation is read is the inner oi the two scales shown on the bottom disc A as indicated at l. Assume that the user Wishes to determine the direct labor price per pound of a coal preparation plant weighing 280,000 pounds. He obtainshis result by inding in the part i.' of the inner arc' or circumference of the disc A, the proper class number for this particular type of equipment, because past experience may show that the direct labor price per pound varies widely with diierent articles or jobs. Let us say that the coal preparation plant is classified under D14. This then is the class number to which the total weight of the coal preparation plant, 2d0,000 pounds, is to be related, in order to determine the cost in dollars per pound. For convenience, I have applied to the intermediate disc B, two scales of weightin pounds, one, 3, for even class numbers, D2 and following, and one, e, for odd class iumbers, D-l and following. I have applied the equation P=llI(W/2 'for one set and the equation F=M(Wr1/4) for the other. As the coal preparation plant is an even numbered class the user reads the total weight, 280,000 pounds, on the even class numbered scale of weight which appears at 3 on the disc B and aligns it with the indicating class No. D14 o! the disc A. When the discs A and B are held with the even class numbered Weight scale having the number 280,000 aligned with the class No. D14, the pointer X on the disc B points to the proper price per pound in dollars as expressed in the scale l of the disc A. This happens to be $00862, as will be shown, for example,

in Figure 4, which is shown as expressing this.

particular problem.

To summarize, the disc A of my slide rule has a class number indication 2, and a price per pound in dollars indication l.

Aobtained in the same manner, depending upon what prior infomation or prior experience 'is embodied in the particular logarithmic scale employed.

- 'I'he ordinary plant produces articles or sets up The disc B has aV 4pointer X, which is opposed to thisprice perl The disc B also carries the Vweight in installations oi widely varying type, wherein the l tion above discussed, only the discs A and B were employed. The purpose of the disc C will later appear. It will be understood, of course, that I can use either two or more discs, or two or more slides, and that I may employ moving members sliding-rectilinearly in relation to each other, instead of rotating in relation to each other. The particular embodiment herein shown is applied to the determination not only of the cost of certain types of work, but of engineering and drafting time. Besides costs, it can be used to determine the number of hours or work and the number of hours of different kinds oi work on different operations needed for the completion of a particular `iob. For example, it can be employed to determine the drafting, time necessary, in plant construction. The various opera* tions can be broken down into ,such individual items as general design, detailing :of machinery, designing of steel Work, building and supports for machinery, detailing of such steel work, buildings and supports, etc. My slide rule serves as a Vguide in planning or scheduling the work of a department, and virtually supersedes the necessity oi checking over cost cards or time records.

As Vabove explained, for cost information only the slides or discs A and B need be employed. For information in relation to drafting time or for the rtime of particular operations, it is necessary to employ also the top disc C. This disc has' forms closely to the outer scale oi the bottom i disc A.' The'scale on the member B which co. operates with the disc C is a third or inner calibration, shown at 5, and is a statement o! weight in pounds calibrated from 100 pounds to 1,000,000. This scale may, for example, indicate the weight oi theparticular plant or object or article about which time information is desired. As this infomation varies with various types oi articles or products I have indicated, ou the member C'. three pointers 1, 8 and 9, relating to the particular types o! product produced by the particular plant the records of which were employed in developing the particular slide rule shown in the accompanying drawings.

Assume that we are again using the example of the 280,000 pound coal washery. Note that one di the three points, 9, indicates a coal preparation plant. Therefore, this particular pointer is aligned with the weight 280,000, on the inner scale of the intermediate disc B. The pointer X of the disc B, in turn, is set at the already established price of $00862. These two known iactors or known facts establish the proper position of the discs B 'and C in relation to the disc A. The total number of hoursvis then indicated on the outermost scale of the disc A and is read oil by the total hour pointer Y, which is located on direct labor price per pound may vary widely l the periphery o! that portion of the-disc'C which 75' of hours in this case is 2210.

If it is desired to break this total into the y hours for speciiic operations, this can be done Iment.

through the indicating members shown on the enlarged portion of the disc C. I indicate thereon a plurality of arcs, each arc being indicated by an index number, from to I3. Obviously this particular numbering and arrangement is a matter of convenience but for the particular plant for which this slide rule was developed I find this a convenient arrangement. Each index number relates to an arc upon which arc are arranged at various points the numbers of the particular operations which form part of the total time consuming operations of the particular devices related to by the index numbers. I employ, for "example, numbers from 06 to Il. which happen to be the last two digits of the operation numbering which I employ in an index 0i operations which is provided for the user of the slide rule. As an example, may relate to the complete general design of the equip- Il'l-may relate to detailing of the ma- 08 may indicate the detailing of the Steel supports. 09 may indicate design of the building, structural steel or wood. I0 may indicate detailing the building or structural steel. Il may indicate checking. These are all factors or operations which can be expressed in necessary drafting time. y

Continuing with our coal washery example, the index number of the coal washery is 2. Reading along the arc indicated by 2l the iirst operation number reached is il. If we set the pointer Z so that its line I0 will pass through the appropriate marginal marking for the number Il, it indicates 132 hours on the outer peripheral scale of hours of the disc A. In other words,

chinery.

-the operation Il, namely checking, for the above mentioned 280,000 pound coal washery, has indicated, from past experience, to be 132 hours. 'This is the expression 'of the past average for checking plants oi this type and size. The next operation, 09, designing the building, of structural steel or wood, proves, from a similar use 0f lthe pointer, to take 218 hours. vThat is to say, past experience indicates that 218 hours oi draftin'g time is necessary for the design of the building of the coal washing plant, whether of structural steel or wood. In moving from left to right along the arc, it will be understood that the operations are not taken in the sequence of perfomance, but that is unimportant. The next operation, 01, detailing of the machinery, is indicated by the pointer, on the marginal scale of the disc A, as involving 350 hours. The next operation Ile, general design, is indicated on the scale as calling for 620 hours. The next two operations, 08 and I0, lumped together, detailing the steel supports and detailing the building, total 890 hours. The time given for .these various operations, when added up, equals the 2210 hours indicated by the marker Y on the mar'- ginal scale; Thus, with .the type of machinery or equipment known, its total( weight known, and its cost' per pound known, the drafting time can be determined, both for the entire device or installation, or for individual operations.

As regards the mechanical make-up of the lslide rule, it will be observed from Figure 5 that [the rotation of the thumb nut I3 about the screwthreaded portion I2 will clamp the washer- Il against the top oi the disc C. The three dieee will thereby be locked alainst the enlarged- Portion II of the screw Il. Note that the washer I4 has ga' sleeve le about which the pointer Z is freely rotatable.' In other words, the discs may be locked together in position but the pointer Z can still freely move; Note also that `the length of the pointer Z is such that it, and

its radial indicating line III, extends outwardly slong the periphery ot the larger or bottom isc A.

It will' be realized that whereas I have describedl and shown a particular application of my device, its details are given largely for purpose of illustration. In other words, no two plants need use an identical slide rule, although the principle of operation may be the-same. The past averages can be readily determined from past records but will of course differ from plant to plant.

The use and operation o! my invention are as follows: f

I have'developed a means for 'obtaining information based on past perfomance, past experience or past average, which is available for determining direct labor hours or labor costs in relation to any manufactured article or articles or in relation to any articles which 'are handled or processed or in any way subjected to the employment of labor. I can be applied to determining hours or time periods necessaryin processing articles and while I ilnd a very practical application of my invention to be the determination of labor hours and labor costs I do not wish to be so limited in my claims unless such limitation appears upon theface of some particular claim or claims. Each can equally well be applied to the determination of price, sales costs, etc. It is, of course, applicable to building or construction work per se or engineering work in general. It is applicable to warehousing, to the handling of goods, to the storage of goods, and of course, to the manufacture and sale of goods.

In a broad sense my invention involves building up or employing a mass of detail obtained from past experience into scales, preferably logarithmic, from which the user can mechanically determine totalsj;v These totals can then be broken down into details as desired. For example, as above described. I can obtain the total labor hours requisite for a given operation or series oi operations, reading off from the pointer Y on the hour scale about the periphery o! the disc A. Or I can break down this total into the particular -individual operations and I provide, on the enlarged portion of the disc C the necessary classification, keyed in index numbers and operation numbers. ior determining the operation times stated, for example, in hours of work. The simplicity of my invention and the saving oi time and effort is simply incalculable. As above stated, I can just as simply determine labor costs in relation to particular installations. articles or steps, relating the total labor costs.

for example, to the total weight of the particular article or jobs involved. I have described the v Similarly, my invention not merely to plant operation, but to bidding, is enormous. v

I claim: f

l. In a sliderule for determining marlufactinea ing costs, a plurality of relatively movable members each having scales thereon, the scale of one of said members being divided into a group of calibrations indicating the class of work being iigured and a group of calibrations indicating price, said groups being in end to end relationsloip, another of said relatively movable members having its edge lying adjacent the edge of tire class and price scale on the rst member and having thereon two scales lying adjacent eacii other and the class indicating scale and cooperating therewith, one oi' said scales being caliloi-ated for svori: in an even numbered class and the other being calibrated ior an odd number-eci class, said two scales progressing in saus/e direction and being oiiset with respectto eacii other, and a single indicating pointer positioned on the edge of said other member and cooperating with the price scale on the irst member so as to indicate price thereon when the mem= bers are moved relative to each other so that a graduation for a known factor on the sosie of the second member in either an odd or an even numbered class registers with its proper class cali= bration on the first member.

2. In a slide rule for determining manufacturlng costs', a plurality of relatively movable members each having scales thereon, the scale of one of said members being divided into a group of calibrations indicating the class of work being figured and a group of calibrations indicating price, said groups being in end to end relation.n ship. the first group being divided into calibrations indicating an even numbered and also an odd numbered class of work with one group forming a continuation of the other and both progressing in the same direction, another of said even numbered class and the other being cali-v orated for an odd numbered class., said two scales progressing in the same direction and being offset with respect to each other, and la single indicating pointer positioned on the edge of said other member and cooperating with the price scale on the mst member so es to indicate price thereon wheny the members are moved relative to each other so that a. graduation for e, known factor on the scale of tlie second member in 'either an odd or an even numbered class registers with its proper cia-m calibration on the drst member.

fi; In a slide rule for dote w i :il time, a piurality of relatively movable members, one of said members having a continuous scale thereon calibrated in hours, a second member having a continuous scale thereon calibrated in pounds, and a third member having indicating pointers on the edge thereof adjacent to the edge of the scale on the second member and cooperating therewith, the pointers indicating diierent classes of work being figured, said third member also having a result pointer on another edge thereof spaced from the first mentioned pointers and lying adjacent to and cooperating with the iiour scale on the first member, the three members cooperating with each other so that movement of one of the class pointers on the third member into registry with a graduation representing a known factor on the scale of the second member causes the result pointer to indicate the result in hours on the scale of the irst member.

l CHRISTIAN P. BERG. 

